The suit was filed Friday in Los Angeles, People magazine reports, citing court papers.
Attorney Alex Weingarten said, "The Tony Awards dropped a piece of the stage on Bret's head, and then instead of doing the right thing, joked about it and played it off for ratings. Bret never wanted to file a lawsuit, but the Tony Awards have left us with no choice. They must be held accountable for almost killing Bret, and that is what we are going to do."
Suing for unspecified damages, Michaels says he has suffered a hemorrhage and poor health since the 2009 accident.
He asserts that he asked producers for instructions where to stand at Radio City Music Hall in New York, but was told to "simply exit the stage from the rear."
Michaels was hit by a piece of falling scenery after performing with his band Poison and the cast of "Rock of Ages." He was knocked to the ground, broke his nose and needed three stitches in his lip.